Quid sit quod cum diis incorporeis deos in caelo corporeos connectat ?(What would be that which connects the corporeal gods in heaven with the incorporeal gods ?)

By the Latin I understand the meaning, but I don't clearly see the grammatical structure of the Greek.(Is this an omittion of the infinitive of sunaptomai ? Can the infinitive of verbs other than einai be omitted ?) Someone please explain to me.